Non-Oriented Electrical Steel Composition Against Processing Hardening
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Solution Overview
Problem
Existing non-oriented electrical steel sheets face challenges in maintaining excellent magnetic properties after processing due to stress-induced deterioration during shearing or punching, leading to increased iron loss and reduced magnetic flux density, and existing solutions like stress relief annealing are costly or difficult to implement.
Innovation Solution
A non-oriented electrical steel sheet composition comprising specific amounts of Si, Mn, Al, Bi, and Ga, with controlled addition ranges and a method involving hot-rolling, cold-rolling, and final annealing, which minimizes processing hardening and maintains magnetic properties without the need for additional stress relief annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stress relief annealing is performed to reduce magnetic deterioration after processing, then magnetic properties are improved, but production cost increases
Solution Approach 1:
The patent applies preliminary action by adding specific alloying elements (Bi: 0.001-0.005 wt%, Ga: 0.001-0.005 wt%) during the steelmaking process to pre-establish resistance against processing-induced magnetic deterioration. This preliminary compositional adjustment eliminates the need for subsequent stress relief annealing, thereby maintaining excellent magnetic properties after shearing or punching without incurring additional annealing costs
Solution Approach 2:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the steel sheet, specifically limiting Si to 1.5-4.0 wt%, Mn to 0.1-1.5 wt%, Al to 0.7-1.5 wt%, and adding trace amounts of Bi and Ga. This parameter optimization creates a microstructure that inherently resists processing hardening, allowing the steel to maintain low iron loss and high magnetic flux density without requiring stress relief annealing
2Loss of energy
If the addition amount of Si, Al, and Mn is increased to reduce iron loss, then eddy current loss is reduced, but magnetic flux density deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the addition amounts of Si (1.5-4.0 wt%), Al (0.7-1.5 wt%), and Mn (0.1-1.5 wt%) to achieve the right balance between eddy current loss reduction and magnetic flux density maintenance. This controlled parameter adjustment ensures that the steel sheet achieves low iron loss while preserving high magnetic flux density
Solution Approach 2:
The patent applies composite materials by creating a multi-element alloy system combining Fe with optimized amounts of Si, Al, Mn, Bi, and Ga. This composite composition works synergistically to reduce eddy current loss through increased resistivity while the specific ratios of alloying elements maintain the magnetic flux density at high levels
3Loss of energy
If the thickness of the steel sheet is decreased to reduce iron loss, then energy efficiency is improved, but productivity and processability are decreased
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition parameters rather than relying solely on thickness reduction. By controlling Si (1.5-4.0 wt%), Al (0.7-1.5 wt%), Mn (0.1-1.5 wt%), Bi (0.001-0.005 wt%), and Ga (0.001-0.005 wt%), the steel achieves low iron loss through reduced eddy current loss and hysteresis loss, eliminating the need to reduce thickness for energy efficiency purposes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The steel sheet achieves low iron loss (W15/50 ≤ 2.7 W/kg) and high magnetic flux density (B1 ≥ 1.02 T) with minimal processing hardening, ensuring efficient energy conversion in motors and generators without additional annealing processes.
Implementation Method 1
the increase in the addition amount of the alloy elements deteriorates the magnetic flux density, the appropriate addition amount and the addition ratio between the addition amounts of Si, Al, and Mn need to be appropriately controlled to ensure excellent iron loss and magnetic flux density
Implementation Method 2
In order to solve the magnetic deterioration by such processing, stress relief annealing is performed
Implementation Method 3
the magnetic properties is greatly decreased by a processing stress to be applied, and there is a difference in magnetic deterioration rate depending on mechanical properties, a microstructure, or the like the steel sheet
Data Source
AI summary
A non-oriented electrical steel sheet according to one embodiment of the present invention comprises: 1.5 to 4.0 wt % of Si; 0.1 to 1.5 wt % of Mn, 0.7 to 1.5 wt % of Al; 0.0001-0.003 wt % of Bi; and 0.0001 to 0.003 wt % of Ga, with the balance comprising Fe and inevitable impurities, and satisfies the following Formula 1.[Al]+[Mn]≥0.87 [Formula 1](here, [Al] and [Mn] represent the contents (wt %) of Al and Mn, respectively.)